Printing



G. R. BRODIE Sept. 3, 1957 PRINTING Filed Sept. 7, 1955 INVENTOR GEORGE R. B RODIE 2,804,693 Patented Sept. 3, 1957 PRINTING George Rogers Brodie, Lower Merion Township, Montgomery County, Pa., assignor to Fredk. H. Levey Company, Inc., New `York, N. Y., a corporation of New York Application September 7, 1955, Serial No. 532,840

10 Claims. (Cl. 344-18) The present invention relates to printing and, more particularly, to improvements in the method and means for setting and drying films of so-called water-set inks following their application to paper or the like. It is especially useful in web-fed printing operations.

'Ihese so-called Water-set inks are specifically designed for quick drying by the application of water vapor and heat to the freshly printed -ink film to produce prints which are proof against offsetting. These inks consist essentially of a pigment and a vehicle containing a resin binder. Various printing inks of this type are known to the industry, each of which may be used with advantage in accordance with this invention. Such inks having a polyglycol base have been used with particular advantage.

An example of such inks are those comprising a waterinsoluble resin dissolved in a water-soluble solvent, e. g. a polyglycol. When brought into contact with steam, water is dissolved in the ink lilm causing the precipitation of the water-insoluble resin.

According to conventional practice, in web-printing, for instance, when using these Water-set inks, the freshly printed web passing from the impression -cylinder of the press is passed through a drying tunnel, maintained at an elevated temperature and usually from 4 to 10 feet long, and while passing therethrough jets of steam are directed against the freshly printed side of the web. The printed web is then passed directly to a rewind stand.

iBy this procedure the steam acts primarily on the outer surface of the ink lm while the inner surface of the film is shielded from the steam by the web. Thus the action yof the steam on the ink iilm has resulted in a drying of the film from the `outer surface inward, and uniformity of drying and optimum binding of the ink to the web have been diiicult to obtain. Further, the drying has not been `as rapid as desired and the required lapparatus has been cumbersome.

I have found that notable improvements in uniformity and rate of drying of such inks, and other advantages hereinafter noted, are obtained by wetting with water the underside of the freshly printed web, i. e. the side opposite from that containing the wet ink lm, and then converting the water to steam by passing the wet side of the web in contact with a hot, substantially imperferate surface, as hereinafter more fully described. By this procedure, the generated steam is forced through the web thus initially coming into contact with the webside of the ink iilm, and effecting its drying from the web outwardly. The passing of the steam through the web may, with advantage, be promoted by maintaining a reduced pressure on the ink-iilm-side of the web, but this is not ordinarily required.

Where desired, steam may also be applied to the freshly printed side of the web by directing jets of steam thereon and this is frequently advantageous, especially where the web is relatively thick or for other reasons offers considerable resistance to the ow of steam therethrough. But usually the generation and application of steam by passing the wetted web in contact with a hot substantially imperforate surface, as just described, will be found adequate.

I have, with particular advantage, effected the drying of the ink tilm by passing the web, wetted as previously described, about the periphery of a drum having a solid substantially imperforate surface maintained at a temperature in excess of the boiling point of water, advantageously within the range of about 225 -350 F. by means of steam.

The optimum temperature of the drum will depend upon the type and thickness of the web, the web speed, the extent of contact between the web and the drum, the amount of water applied to the web and the particular type lof ink being used. Similarly, the optimum amount of water to be applied to the web will depend upon the type of web and the type and amount of ink being applied thereto. It is especially advantageous, therefore, that the amount of water applied to the web and the temperature of the drum and the arc of contact be independently Variable over Ia considerable range to accommodate various conditions.

Vario-us means may be used for applying the water to the underside of the web. For instance, the water may be applied by spraying or by conventional dampening mechanisms used in offset printing, composed, for instance, of a knurlcd roller dipping into a fountain of w-ater and rotating in contact with a cloth-covered roller, terry cloth for instance, which in turn rotates in contact with the underside of the web. Or any other type of dampening mechanism may be used. However, it is especially desirable that the water be uniformly applied to the underside of the web -or other printed sheet, and that the dampening means be capable of such uniform application.

Since the purpose of the water is that of setting the ink, the amount of water applied to the web is with advantage maintained just suicient to accomplish that purpose, though larger amounts of water may be used where permitted by the type of paper constituting the web. It will be recognized that some papers weaken rapidly when wetted, others tend to wrinkle or are otherwise damaged by excess water, and under such conditions the amount `of water applied should be restricted. Other papers may be wetted to a much greater extent without harm and 'under such conditions a substantial excess of water over that required to set the ink films may be used without deleterious results.

In normal printing operations, the web speed will usually fall within the range of 300 feet to 1000 feet per minute but may run as high as 2000 feet per minute. Since the web must be in contact with the drum for a sufficient peri-od of time to effect adequate drying of the ink and the web, the contact time and temperature yof the drum will depend upon the web speed and the amounts of ink and water applied to the web, and also upon the web thickness.

The period of time during which the web is in contact with the drum may be varied by varying the web speed or by changing the diameter of the drum or by varying the arc of Contact between the web and the drum surface. In one particularly advantageous aspect of the invention, the contact time'may be varied independently of the web speed or drum size by varying the point at which the web breaks contact with the drum, i. e. by varying the arc of contact between the web and the drum, as hereinafter more fully described.

It is usually desirable that some moisture be allowed to remain in the web. It is also necessary to avoid overheating the web and to avoid permitting the web to remain at deleterious temperatures for extended periods. In accordance with this invention, I may so coordinate the temperature of the drum, and the time of contact that the requisite amount of moisture remains in the web and the temperature of the web does not exceed 2l2250 F. even though the drum temperature may substantially exceed that range.

By reason of the presence of water between the web and the hot drum surface, the web'may be allowed to remain on the hot surface for a considerable period'v of time without heating the paper to the drum temperature, usually for a period of several'seconds, without damaging the paper. Thisextended period of heating also promotes the drying of the ink.

As a further precaution against damaging the paper web by prolonged exposure to high heat, I provide in accordance with one modication of my invention, one or more cooling rolls positioned in the path of the web leaving the drum and adapted to be maintained at a relatively low temperature of the order of 50-100 F. by passing the cool uid therethrough, for instance water. By this means the temperature of the web leaving the heatingdrurn is quickly cooled to a'y safe temperature thus avoiding damaging the paper even when heated to temperatures as high as 300 F. before leaving the drum.

The invention will be further described and illustrated with reference to the accompanying drawing which represents conventionally and diagrammaticallyl apparatus which has been used with'particular advantage in carrying out the process. It will be understood, however, that the invention is not restricted in scope to the particulars of this illustration.

The single gure of the drawing is a vertical, sectional view, in which the impression cylinder of a rotary webfed press is indicated at 1 and a plate cylinder or blanket roll is indicated at 2. The entering web 3 passes over the tension roll 4 and around the impression cylinder 1. While passing around the impression cylinder, the ink film is applied to the web in the customary manner,V as by means of one or more plate cylinders or blanket rollsl indicated at 2. The web leaving the impression cylinder, and havingfreshly printed ink lms on its upper side, is passed over tension roller 5 and then in contact with moistening roll 6.

Water is maintained in the fountain 7 and is picked up therefrom by a fountain roll 3 which applies the water to the intermediate roll 9 operating in contact with the dampening roll 6: The rate at which water is applied to the dampening roll may be varied by varying the speed of rotation of the fountain roll 8 driven through variablespeed unit 17 and drive-chain 18. l

From the dampening roll 6 the web which has been uniformly wetted with water on its underside, passes directly to steam heated drum 10 having a substantially im perforate peripheralsurface which is maintained at the desired temperature by passing steam through the drum in the conventional manner. A portion of the periphery of the drum is enclosed by the oven 11, the lower por- In such case, the webs may be taken oft from different points in the periphery of the drum by the appropriate positioning of rolls 15. By so positioning the roll or rolls 15, the contact between the web and the drum may be varied from 1/2 to 2/s or to 3A of the periphery of the drum.

For varying the point or points at which the web leaves the drum 10, a plurality of rolls may be protion of which is partitioned from the upper portion by partition 12 having a perforated arcuate section and is adapted to be maintained at a subatmospheric pressure by means of a suction fan 19 to which itis connected by suction pipe 13, so as to promote the passing of the generated steam through the web.

Steam bars 14 are positioned in the upper portion of oven 11 and are adapted to direct jets of steam onto the upper surface of the web as it passes through the oven about the steam drum. These steam jets 14 are not essential but may frequently be used with advantage as previously described.

On leaving the drum, the web passes about roll 15 and from thence about water-cooled rolls `16: The position of roll 15 may be changed at will, as indicated in dotted lines, in order to vary the arc of contact between the web and the steam drum. Where desired, the steam drum and the oven may be of suicient width to accommodate more than'one web, for instance,.in4 a Vdouble-:ander press.

vided, spaced in xed positions somewhat as indicated, and the arc of contact Varied by threading the web around a selected roll. So that the arc of contact may be varied without rethreading the web, it is preferred to use a single roll 15 rotatably mounted at each end in bearing blocks movably supported in known manner in channels 20 extending along segments of the side press frames indicated at 21.

It will be understood that the length of the drum, oven, steam jets 14 and thevarious cylinders and rolls described will be at least cqualfto the Width of the web.

In view of the foregoing disclosure, it will be understood that the various operating conditions are interdependent and that no overall conditions or combination of conditions can be prescribed, but that the temperature of the drum and time of contact of the web therewith and the amount of water applied to the underside of the web must be varied depending upon the characteristics of the web and the printed matter thereon. By suitable variations in these conditions, which are readily determinable by one familiar with this art, the invention is applicable to all types of paper and webs of like material which are not impervious to the passing of steam therethrough and which can be wettedwith water without serious damage.

The invention is especially useful in printing on relatively thin paper, for instance bread wrapper stock, but is also applicable to the printing on heavier paper stocks, for instance those used for cement bag covers. Usually with heavier stock, it is desirable to apply a greater proportion of water andto keep the web in contact with the drum for a longer period'of time so as to effect adequate drying.

The type of water used is not critical so long as it docs not contain impurities which would stain the printed sheet. In general ordinary city water is satisfactory.

It may be desirable in some instances to heat the water before applying it to the underside of the Web, but usually they'added expense of heating the water is not justified.

In printing a web of paper of the type generally known as bread wrapper stock, for instance, using a polyglycol base printing ink, the ink may be satisfactorily set and dried lat a web speed of about 500 ft. per minute with no application of steam to the upper side of the web. In such operation', :a steam-heated drum 48" in diameter may be used with advantage utilizing only 7 5 of the drum circumference. The cooling rolls 16 may be maintained at a temperature of about 70 F. and a reduced pressure of about 11/2" of water maintained in the lower portion of the oven.

In operations where steam is' also :applied to the upper side of the'web, steamvunder a pressure of about l lb. gauge may be `applied to the steam bars 14, from any suitable source, and is jetted under the upper surface of the web, usually at' the highest possible rate without injury to the paper.

I claim:

l. Method of setting'and drying lms of water-set printing ink on a freshly printed sheet which comprises the following steps in sequence, wetting with water the underside of the printed sheet and passing the wetted side of the sheet in contact with an imperforate solid surface while maintaining the surface at a temperature in excess of the boiling point ofwater, thereby converting the water to steam and causing the resultant steam to pass through the sheet intocontact with the ink lm thereon.

Y lMethod of'v setting and drying lrnsV of water-set printing ink on-awcb as it passes continuously from the impression cylinder of a web-fed printing press which comprises the following steps in sequence, wetting with water the underside of the web passing from the impression cylinder and passing the wetted side of the web in contact with an imperforate solid surface while main taining the surface at a temperature in excess of the boiling point of water, thereby converting the water to steam and causing the resultant steam to pass through the web into contact with the ink film thereon.

3. Method of setting and drying films of water-set printing ink on a web as it passes continuously from the impression cylinder of a web-fed printing press which comprises the following steps in sequence, wetting with water the underside of the web passing from the impression cylinder and thereafter passing the web about a cylindrical drum having an imperforate peripheral surface with the wetted side of the web in contact with that surface, and maintaining said drum surface `at a temperature in excess of the boiling point of water, thereby converting the water to steam and causing the resultant steam to pass through the web into contact with the ink film on the other side of the web.

4. Method of setting and drying films of water-set printing ink on a web as it passes continuously from the impression cylinder of a Web-fed printing press which comprises the following steps in sequence, wetting with water the underside of the web passing from the impression cylinder, passing the web about a cylindrical drum having an imperforate peripheral surface with the wetted side of the web in contact with that surface and maintaining said drum surface at a temperature in excess of the boiling point of wat-er, thereby converting the water to steam and causing the thus generated steam to pass through the web into contact with the ink film on the other side of the web and heating the web, and substantially immediately thereafter passing the underside of the web in contact with a solid surface maintained at a temperature substantially below the boiling point of Water.

5. In conjunction with a rotary printing press adapted to print films of water-set printing ink on a continuous web as it passes in contact with an impression cylinder, means for setting land drying the ink films on the web comprising a rotatably mounted drum positioned in the path of the web passing from the impression cylinder and having a substantially imperforate peripheral surface, means for maintaining the peripheral surface of the drum at a temperature in excess of the boiling point of water, means for rotating said drum and means for wetting with water the underside of the web as it passes from the impression cylinder to the heated drum.

6. In conjunction with a rotary printing press adapted to print films of water-set printing ink on a continuous web as it passes in contact with an impression cylinder, means for setting and drying the ink lms on the web comprising a rotatably mounted drum positioned in the path of the web passing from the impression cylinder and having a substantially imperforate peripheral surface, means for maintaining the peripheral surface of the drum at a temperature in excess of the boiling point of water, means for rotating said drum, means for wet-ting with Water the underside of the web as it passes from the impression cylinder to the heated drum and at least one roll positioned in the path of the web leaving the drum adapted to be cooled by passing a cooling fluid therethrough.

7. In conjunction with a rotary printing press adapted to print films of water-set printing ink on a continuous web as it passes in contact with an impression cylinder, means `for setting and drying the ink film on the web comprising a rotatably mounted drum positioned in the path of the web passing from the impression cylinder and having a substantially imperforate peripheral surface, means for maintaining the peripheral surface of the drum at a temperature in excess of the boiling point of water, means for rotating said drum, means for wetting with water the underside of the web as it passes from the impression cylinder to the heated drum, and means for varying the arc of contact between the web and the drum surface.

8. In conjunction with a rotary printing press adapted to print films of water-set printing ink on a continuous web as it passes in contact with an impression cylinder, means for setting and drying the ink film on the web comprising a rotatably mounted drum positioned in the path of the web passing from the impression cylinder and having a substantially imperforate peripheral surface, means for maintaining the peripheral surface of the drum at a temperature in excess of the boiling point of water, means for rotating said drum, means for wetting with water the underside of the web as it passes from the impression cylinder to the heated drum and means for Varying the amount of water thus applied to the web.

9. In conjunction with a rotary printing press adapted to print lms of water-set printing ink on a continuous web as it passes in contact with an impression cylinder, means for setting and drying the ink film on the web comprising a rotatably mounted drum positioned in the path of the web passing from the impression cylinder and having a substantially imperforate peripheral surface, means for maintaining the peripheral surface of the drum at a temperature in excess of the boiling point of water, means for rotating said drum, a dampening roll positioned in the path of the web as it passes from the impression cylinder to the heated drum and adapted to wet the underside of the web with water, means for applying water to the periphery of the dampening roll and means for varying the rate at which water is thus applied to the dampening roll.

10. In conjunction with a rotary printing press adapted to print films of water-set printing ink on a continuous web as it passes in contact with an impression cylinder, means for setting and drying the ink film on the web comprising a rotatably mounted drum positioned in the path of the web passing from the impression cylinder and having a substantially imperforate peripheral surface, means for maintaining the peripheral surface of the drum at a temperature is excess of the boiling point of water, means for rotating said drum, means for wetting with water the underside of the web as it passes from the impression cylinder to the drum and means for subjecting the web to a reduced pressure during the latter part of its period of contact with the heated drum.

References Cited in the file of this patent UNITED STATES PATENTS 1,115,551 Lamey Nov. 3, 1914 2,157,388 MacArthur May 9, 1939 2,402,237 Carder June 18, 1946 2,642,676 Grimm June 23, 1953 2,673,385 Williamson et al. s- Mar. 30, 1954 2,731,732 Harris et al. Jan. 24, 1956 

